Earlier quoted context omitted.
In Brazil this is a GREAT reason to NOT use it. In fact phone operators for a while tried to ban whatsapp here, SMS prices in Brazil are just nuts (it is normal for an SMS cost fifty cents or so, sometimes even more, a full SMS conversation can cost you several days worth of food). Everyone here just uses whatsapp, because of how ridiculous SMS prices are.
It must be a market difference. Here in north america, SMS is the "default" way you message new contacts, and the majority of chats I have with people are over SMS. SMS is free and unlimited on virtually every phone plan available.
That's what I love about these forums, is getting the cultural experiences of other people and finding out they're not always the same as your experiences. Very eye-opening.